So far, for the small and medium-sized electric contacts, contact materials with good electroconductivity comprising gold, gold alloy, silver and silver alloy have been used because of low contacting force. With these contact materials, however, when the number of works of switching-on and -off increases, the exhaustion reaches the substrate metal because of low hardness (Hv 100-200) and low melting point (900.degree.-1060.degree. C.) resulting in the scattering of exhausted powder onto the surface of contact. Hence, the contacting resistance etc. increased leading to the instability. Moreover, the time-lag (poor restoration) was caused due to the adherence and locking of the surface of contact leading to a drawback of remarkably short life of contact. On the other hand, in the cases of lead switch etc., if using W, Mo, etc. being metals with high melting point from the reasons of low contacting pressure and difficulty in providing thick layer of contact, the increase in the contacting resistance cannot be prevented. So, plated contacts with noble metals such as Rh, Ru, etc. are broadly used.
However, the Rh contact has a drawback that the contacting resistance increases with organic gases containing in the atmosphere and organic gases previously adsorbed onto the surface. Moreover, it is impossible to give the plating onto easily oxidizable contact strips or lead pieces of Fe, Ni, etc. and it is required to plate intervening plated layers of Au, Ag, Cu, etc. For this reason, effective plating thickness decreases and the process becomes complicated on production leading to a drawback of high-processing price for contact.